The present invention deals with an open-type mixer for rubber and plastics processing, which is provided with an additional roll.
It is known that open mills or mixers are essential in the processing of rubber and plastic material to obtain mixes with the desired compound and degree of homogeneity and temperature. They may be used either as a first stage of processing, as they receive the mix components directly from a hopper, or as second stage downstream of a closed mixer, in which case they have also a cooling function. Inside thereof in fact a cooling fluid flows, usually water.
It is however known that these prior art mixers require a number of subsequent passages of the same compound batch, before the latter can be considered ready to be used in a rubber moulding press. Furthermore, if the compound batch has already passed upstream through a closed mixer, in any case a multiplicity of passes will be necessary to reduce the mix temperature. In order to reduce the working time, it would be possible to cause the same compound batch to pass subsequently through at least a second open mixer, operating in series with the first one, but the costs and dimensions involved would be excessive, thus seriously affecting the overall economy of the process.